The packdeps package

This provides a library and command line tool for checking if the upper bounds in your package's dependency list excludes the newest package available. The code was originally available only as a web interface at http://packdeps.haskellers.com/, but is now available for standalone use as well.

The command line tool has an incredibly simple interface: simply pass it a list of cabal files, and it will tell you what dependencies- if any- are restricted.